Peeling apparatus

Abstract

A peeling apparatus includes: an ingot holding unit holding an ingot with an ingot portion corresponding to a wafer being faced up; an ultrasonic wave oscillating unit which has an end face facing the ingot portion corresponding to the wafer and oscillates an ultrasonic wave; a water supplying unit supplying water to an area between the ingot portion corresponding to the wafer and the end face of the ultrasonic wave oscillating unit; and a peeling unit that holds the ingot portion corresponding to the wafer with suction and peels off the wafer from the ingot.

What is claimed is: 
     
       1. A peeling apparatus for peeling off a wafer from an ingot formed therein with a peel-off layer by applying a laser beam of such a wavelength as to be transmitted through the ingot, with a focal point of the laser beam positioned at a depth corresponding to a thickness of the wafer, the peeling apparatus comprising:
 an ingot holding unit holding the ingot with an ingot portion corresponding to the wafer being faced up; and 
 a moving mechanism attached to: 
 an ultrasonic wave oscillating unit having an end face facing the ingot portion corresponding to the wafer and which oscillates an ultrasonic wave; 
 a water supplying unit supplying water to an area between the ingot portion corresponding to the wafer and the end face of the ultrasonic wave oscillating unit; and 
 a peeling unit configured to hold the ingot portion corresponding to the wafer with suction and peels off the wafer from the ingot, 
 wherein the moving mechanism moves the ultrasonic wave oscillating unit, the water supplying unit and the peeling unit. 
 
     
     
       2. The peeling apparatus according to  claim 1 , wherein the ingot is a single crystal SiC ingot having a c-axis and a c-plane orthogonal to the c-axis, and
 the peel-off layer is a peel-off layer including a modified portion and a crack, the modified portion and the crack being formed by a process in which the laser beam is applied to the single crystal SiC ingot, with the focal point of the laser beam positioned at the depth corresponding to the thickness of the wafer from an end face of the single crystal SiC ingot, to form the modified portion in which SiC has been separated into Si and C and the crack which is formed isotropically in the c-plane. 
 
     
     
       3. The peeling apparatus according to  claim 2 ,
 wherein the ingot is the single crystal SiC ingot in which the c-axis is inclined relative to a perpendicular to the end face of the single crystal SiC ingot and an off angle is formed by the c-plane and the end face of the single crystal SiC ingot, and 
 the peel-off layer is formed by forming the modified portion continuously in a direction orthogonal to the direction in which the off angle is formed and forming the crack isotropically in the c-plane, and putting the single crystal SiC ingot and the focal point into relative indexing feeding in the direction in which the off angle is formed, in such a range as not to exceed the width of the crack, to form the modified layer continuously in the direction orthogonal to the direction in which the off angle is formed and to sequentially form cracks isotropically in the c-plane from the modified portion. 
 
     
     
       4. The peeling apparatus according to  claim 1 , wherein the moving mechanism is attached to a first moving piece and a second moving piece, said first moving piece including said ultrasonic wave oscillating unit and said water supplying unit and said second moving piece including said peeling unit, wherein said first moving piece and said second moving piece are moved independently of each other. 
     
     
       5. The peeling apparatus according to  claim 4 , wherein said first moving piece and said second moving piece are each moved in a direction parallel to a surface of the ingot and said ultrasonic wave oscillating unit and said peeling unit are each moved transversely to the surface of the ingot. 
     
     
       6. The peeling apparatus according to  claim 1 , wherein said water supplying unit includes a nozzle that directs water to an area between the ultrasonic wave oscillating unit and the ingot.